1 /*
2 * Copyright 1995-2021 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10 #define OPENSSL_SUPPRESS_DEPRECATED /* for BIO_get_callback */
11
12 #include <stdio.h>
13 #include <errno.h>
14 #include "internal/cryptlib.h"
15 #include <openssl/buffer.h>
16 #include <openssl/evp.h>
17 #include "internal/bio.h"
18
19 static int enc_write(BIO *h, const char *buf, int num);
20 static int enc_read(BIO *h, char *buf, int size);
21 static long enc_ctrl(BIO *h, int cmd, long arg1, void *arg2);
22 static int enc_new(BIO *h);
23 static int enc_free(BIO *data);
24 static long enc_callback_ctrl(BIO *h, int cmd, BIO_info_cb *fps);
25 #define ENC_BLOCK_SIZE (1024*4)
26 #define ENC_MIN_CHUNK (256)
27 #define BUF_OFFSET (ENC_MIN_CHUNK + EVP_MAX_BLOCK_LENGTH)
28
29 typedef struct enc_struct {
30 int buf_len;
31 int buf_off;
32 int cont; /* <= 0 when finished */
33 int finished;
34 int ok; /* bad decrypt */
35 EVP_CIPHER_CTX *cipher;
36 unsigned char *read_start, *read_end;
37 /*
38 * buf is larger than ENC_BLOCK_SIZE because EVP_DecryptUpdate can return
39 * up to a block more data than is presented to it
40 */
41 unsigned char buf[BUF_OFFSET + ENC_BLOCK_SIZE];
42 } BIO_ENC_CTX;
43
44 static const BIO_METHOD methods_enc = {
45 BIO_TYPE_CIPHER,
46 "cipher",
47 bwrite_conv,
48 enc_write,
49 bread_conv,
50 enc_read,
51 NULL, /* enc_puts, */
52 NULL, /* enc_gets, */
53 enc_ctrl,
54 enc_new,
55 enc_free,
56 enc_callback_ctrl,
57 };
58
BIO_f_cipher(void)59 const BIO_METHOD *BIO_f_cipher(void)
60 {
61 return &methods_enc;
62 }
63
enc_new(BIO * bi)64 static int enc_new(BIO *bi)
65 {
66 BIO_ENC_CTX *ctx;
67
68 if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL) {
69 ERR_raise(ERR_LIB_EVP, ERR_R_MALLOC_FAILURE);
70 return 0;
71 }
72
73 ctx->cipher = EVP_CIPHER_CTX_new();
74 if (ctx->cipher == NULL) {
75 OPENSSL_free(ctx);
76 return 0;
77 }
78 ctx->cont = 1;
79 ctx->ok = 1;
80 ctx->read_end = ctx->read_start = &(ctx->buf[BUF_OFFSET]);
81 BIO_set_data(bi, ctx);
82 BIO_set_init(bi, 1);
83
84 return 1;
85 }
86
enc_free(BIO * a)87 static int enc_free(BIO *a)
88 {
89 BIO_ENC_CTX *b;
90
91 if (a == NULL)
92 return 0;
93
94 b = BIO_get_data(a);
95 if (b == NULL)
96 return 0;
97
98 EVP_CIPHER_CTX_free(b->cipher);
99 OPENSSL_clear_free(b, sizeof(BIO_ENC_CTX));
100 BIO_set_data(a, NULL);
101 BIO_set_init(a, 0);
102
103 return 1;
104 }
105
enc_read(BIO * b,char * out,int outl)106 static int enc_read(BIO *b, char *out, int outl)
107 {
108 int ret = 0, i, blocksize;
109 BIO_ENC_CTX *ctx;
110 BIO *next;
111
112 if (out == NULL)
113 return 0;
114 ctx = BIO_get_data(b);
115
116 next = BIO_next(b);
117 if ((ctx == NULL) || (next == NULL))
118 return 0;
119
120 /* First check if there are bytes decoded/encoded */
121 if (ctx->buf_len > 0) {
122 i = ctx->buf_len - ctx->buf_off;
123 if (i > outl)
124 i = outl;
125 memcpy(out, &(ctx->buf[ctx->buf_off]), i);
126 ret = i;
127 out += i;
128 outl -= i;
129 ctx->buf_off += i;
130 if (ctx->buf_len == ctx->buf_off) {
131 ctx->buf_len = 0;
132 ctx->buf_off = 0;
133 }
134 }
135
136 blocksize = EVP_CIPHER_CTX_get_block_size(ctx->cipher);
137 if (blocksize == 1)
138 blocksize = 0;
139
140 /*
141 * At this point, we have room of outl bytes and an empty buffer, so we
142 * should read in some more.
143 */
144
145 while (outl > 0) {
146 if (ctx->cont <= 0)
147 break;
148
149 if (ctx->read_start == ctx->read_end) { /* time to read more data */
150 ctx->read_end = ctx->read_start = &(ctx->buf[BUF_OFFSET]);
151 i = BIO_read(next, ctx->read_start, ENC_BLOCK_SIZE);
152 if (i > 0)
153 ctx->read_end += i;
154 } else {
155 i = ctx->read_end - ctx->read_start;
156 }
157
158 if (i <= 0) {
159 /* Should be continue next time we are called? */
160 if (!BIO_should_retry(next)) {
161 ctx->cont = i;
162 i = EVP_CipherFinal_ex(ctx->cipher,
163 ctx->buf, &(ctx->buf_len));
164 ctx->ok = i;
165 ctx->buf_off = 0;
166 } else {
167 ret = (ret == 0) ? i : ret;
168 break;
169 }
170 } else {
171 if (outl > ENC_MIN_CHUNK) {
172 /*
173 * Depending on flags block cipher decrypt can write
174 * one extra block and then back off, i.e. output buffer
175 * has to accommodate extra block...
176 */
177 int j = outl - blocksize, buf_len;
178
179 if (!EVP_CipherUpdate(ctx->cipher,
180 (unsigned char *)out, &buf_len,
181 ctx->read_start, i > j ? j : i)) {
182 BIO_clear_retry_flags(b);
183 return 0;
184 }
185 ret += buf_len;
186 out += buf_len;
187 outl -= buf_len;
188
189 if ((i -= j) <= 0) {
190 ctx->read_start = ctx->read_end;
191 continue;
192 }
193 ctx->read_start += j;
194 }
195 if (i > ENC_MIN_CHUNK)
196 i = ENC_MIN_CHUNK;
197 if (!EVP_CipherUpdate(ctx->cipher,
198 ctx->buf, &ctx->buf_len,
199 ctx->read_start, i)) {
200 BIO_clear_retry_flags(b);
201 ctx->ok = 0;
202 return 0;
203 }
204 ctx->read_start += i;
205 ctx->cont = 1;
206 /*
207 * Note: it is possible for EVP_CipherUpdate to decrypt zero
208 * bytes because this is or looks like the final block: if this
209 * happens we should retry and either read more data or decrypt
210 * the final block
211 */
212 if (ctx->buf_len == 0)
213 continue;
214 }
215
216 if (ctx->buf_len <= outl)
217 i = ctx->buf_len;
218 else
219 i = outl;
220 if (i <= 0)
221 break;
222 memcpy(out, ctx->buf, i);
223 ret += i;
224 ctx->buf_off = i;
225 outl -= i;
226 out += i;
227 }
228
229 BIO_clear_retry_flags(b);
230 BIO_copy_next_retry(b);
231 return ((ret == 0) ? ctx->cont : ret);
232 }
233
enc_write(BIO * b,const char * in,int inl)234 static int enc_write(BIO *b, const char *in, int inl)
235 {
236 int ret = 0, n, i;
237 BIO_ENC_CTX *ctx;
238 BIO *next;
239
240 ctx = BIO_get_data(b);
241 next = BIO_next(b);
242 if ((ctx == NULL) || (next == NULL))
243 return 0;
244
245 ret = inl;
246
247 BIO_clear_retry_flags(b);
248 n = ctx->buf_len - ctx->buf_off;
249 while (n > 0) {
250 i = BIO_write(next, &(ctx->buf[ctx->buf_off]), n);
251 if (i <= 0) {
252 BIO_copy_next_retry(b);
253 return i;
254 }
255 ctx->buf_off += i;
256 n -= i;
257 }
258 /* at this point all pending data has been written */
259
260 if ((in == NULL) || (inl <= 0))
261 return 0;
262
263 ctx->buf_off = 0;
264 while (inl > 0) {
265 n = (inl > ENC_BLOCK_SIZE) ? ENC_BLOCK_SIZE : inl;
266 if (!EVP_CipherUpdate(ctx->cipher,
267 ctx->buf, &ctx->buf_len,
268 (const unsigned char *)in, n)) {
269 BIO_clear_retry_flags(b);
270 ctx->ok = 0;
271 return 0;
272 }
273 inl -= n;
274 in += n;
275
276 ctx->buf_off = 0;
277 n = ctx->buf_len;
278 while (n > 0) {
279 i = BIO_write(next, &(ctx->buf[ctx->buf_off]), n);
280 if (i <= 0) {
281 BIO_copy_next_retry(b);
282 return (ret == inl) ? i : ret - inl;
283 }
284 n -= i;
285 ctx->buf_off += i;
286 }
287 ctx->buf_len = 0;
288 ctx->buf_off = 0;
289 }
290 BIO_copy_next_retry(b);
291 return ret;
292 }
293
enc_ctrl(BIO * b,int cmd,long num,void * ptr)294 static long enc_ctrl(BIO *b, int cmd, long num, void *ptr)
295 {
296 BIO *dbio;
297 BIO_ENC_CTX *ctx, *dctx;
298 long ret = 1;
299 int i;
300 EVP_CIPHER_CTX **c_ctx;
301 BIO *next;
302 int pend;
303
304 ctx = BIO_get_data(b);
305 next = BIO_next(b);
306 if (ctx == NULL)
307 return 0;
308
309 switch (cmd) {
310 case BIO_CTRL_RESET:
311 ctx->ok = 1;
312 ctx->finished = 0;
313 if (!EVP_CipherInit_ex(ctx->cipher, NULL, NULL, NULL, NULL,
314 EVP_CIPHER_CTX_is_encrypting(ctx->cipher)))
315 return 0;
316 ret = BIO_ctrl(next, cmd, num, ptr);
317 break;
318 case BIO_CTRL_EOF: /* More to read */
319 if (ctx->cont <= 0)
320 ret = 1;
321 else
322 ret = BIO_ctrl(next, cmd, num, ptr);
323 break;
324 case BIO_CTRL_WPENDING:
325 ret = ctx->buf_len - ctx->buf_off;
326 if (ret <= 0)
327 ret = BIO_ctrl(next, cmd, num, ptr);
328 break;
329 case BIO_CTRL_PENDING: /* More to read in buffer */
330 ret = ctx->buf_len - ctx->buf_off;
331 if (ret <= 0)
332 ret = BIO_ctrl(next, cmd, num, ptr);
333 break;
334 case BIO_CTRL_FLUSH:
335 /* do a final write */
336 again:
337 while (ctx->buf_len != ctx->buf_off) {
338 pend = ctx->buf_len - ctx->buf_off;
339 i = enc_write(b, NULL, 0);
340 /*
341 * i should never be > 0 here because we didn't ask to write any
342 * new data. We stop if we get an error or we failed to make any
343 * progress writing pending data.
344 */
345 if (i < 0 || (ctx->buf_len - ctx->buf_off) == pend)
346 return i;
347 }
348
349 if (!ctx->finished) {
350 ctx->finished = 1;
351 ctx->buf_off = 0;
352 ret = EVP_CipherFinal_ex(ctx->cipher,
353 (unsigned char *)ctx->buf,
354 &(ctx->buf_len));
355 ctx->ok = (int)ret;
356 if (ret <= 0)
357 break;
358
359 /* push out the bytes */
360 goto again;
361 }
362
363 /* Finally flush the underlying BIO */
364 ret = BIO_ctrl(next, cmd, num, ptr);
365 break;
366 case BIO_C_GET_CIPHER_STATUS:
367 ret = (long)ctx->ok;
368 break;
369 case BIO_C_DO_STATE_MACHINE:
370 BIO_clear_retry_flags(b);
371 ret = BIO_ctrl(next, cmd, num, ptr);
372 BIO_copy_next_retry(b);
373 break;
374 case BIO_C_GET_CIPHER_CTX:
375 c_ctx = (EVP_CIPHER_CTX **)ptr;
376 *c_ctx = ctx->cipher;
377 BIO_set_init(b, 1);
378 break;
379 case BIO_CTRL_DUP:
380 dbio = (BIO *)ptr;
381 dctx = BIO_get_data(dbio);
382 dctx->cipher = EVP_CIPHER_CTX_new();
383 if (dctx->cipher == NULL)
384 return 0;
385 ret = EVP_CIPHER_CTX_copy(dctx->cipher, ctx->cipher);
386 if (ret)
387 BIO_set_init(dbio, 1);
388 break;
389 default:
390 ret = BIO_ctrl(next, cmd, num, ptr);
391 break;
392 }
393 return ret;
394 }
395
enc_callback_ctrl(BIO * b,int cmd,BIO_info_cb * fp)396 static long enc_callback_ctrl(BIO *b, int cmd, BIO_info_cb *fp)
397 {
398 BIO *next = BIO_next(b);
399
400 if (next == NULL)
401 return 0;
402
403 return BIO_callback_ctrl(next, cmd, fp);
404 }
405
BIO_set_cipher(BIO * b,const EVP_CIPHER * c,const unsigned char * k,const unsigned char * i,int e)406 int BIO_set_cipher(BIO *b, const EVP_CIPHER *c, const unsigned char *k,
407 const unsigned char *i, int e)
408 {
409 BIO_ENC_CTX *ctx;
410 BIO_callback_fn_ex callback_ex;
411 #ifndef OPENSSL_NO_DEPRECATED_3_0
412 long (*callback) (struct bio_st *, int, const char *, int, long, long) = NULL;
413 #endif
414
415 ctx = BIO_get_data(b);
416 if (ctx == NULL)
417 return 0;
418
419 if ((callback_ex = BIO_get_callback_ex(b)) != NULL) {
420 if (callback_ex(b, BIO_CB_CTRL, (const char *)c, 0, BIO_CTRL_SET,
421 e, 1, NULL) <= 0)
422 return 0;
423 }
424 #ifndef OPENSSL_NO_DEPRECATED_3_0
425 else {
426 callback = BIO_get_callback(b);
427
428 if ((callback != NULL) &&
429 (callback(b, BIO_CB_CTRL, (const char *)c, BIO_CTRL_SET, e,
430 0L) <= 0))
431 return 0;
432 }
433 #endif
434
435 BIO_set_init(b, 1);
436
437 if (!EVP_CipherInit_ex(ctx->cipher, c, NULL, k, i, e))
438 return 0;
439
440 if (callback_ex != NULL)
441 return callback_ex(b, BIO_CB_CTRL | BIO_CB_RETURN, (const char *)c, 0,
442 BIO_CTRL_SET, e, 1, NULL);
443 #ifndef OPENSSL_NO_DEPRECATED_3_0
444 else if (callback != NULL)
445 return callback(b, BIO_CB_CTRL, (const char *)c, BIO_CTRL_SET, e, 1L);
446 #endif
447 return 1;
448 }
449